Wang Z, Danscher G, Mook Jo S, Shi Y, Schrøder H D
Department of Neurobiology, Institute of Anatomy, University of Aarhus, DK-8000, Aarhus C, Denmark.
Brain Res. 2001 May 4;900(1):80-7. doi: 10.1016/s0006-8993(01)02261-2.
The zinc selenide autometallographic (ZnSeAMG) technique for tracing the retrograde axonal transport of zinc ions in zinc-enriched (ZEN) neurons was used to map the distribution of ZEN neuronal somata in rat spinal cord. After a local injection of sodium selenide into the dorsal or ventral horn, ZnSeAMG-labeled ZEN neurons appeared in Rexed's laminae V, VII and X while laminae I and II were void. A few scattered ZEN somata were observed in the remaining laminae. The labeled neurons differed in shape and size, and the relatively high level of labeled somata around the injection site suggests that many ZEN neurons have relatively short axons or boutons en passage close to the neuronal origin. Ultrastructurally, the retrogradely transported zinc selenide clusters were found in the lysosomes of ZEN somata and proximal dendrites. Electron microscopic studies also revealed two different kinds of ZEN terminals: (1) terminals with flat synaptic vesicles making symmetric synaptic contacts; and (2) terminals with round vesicles making asymmetric synaptic contacts. The present study suggests the existence of propriospinal systems of ZEN neurons comprising both segmental and intersegmental ZEN connections and having either inhibitory or excitatory ZEN terminals. The ZEN neurons seem to form a vast network of terminals located primarily in the gray matter, but also contacting dendrites radiating into the white matter. Important functions of this rather massive system of ZEN terminals can not be deduced from our present knowledge, but the systems appear to be involved in both motor and sensory functions.
利用硒化锌自动金相术（ZnSeAMG）追踪富含锌（ZEN）神经元中锌离子的逆行轴突运输，以绘制大鼠脊髓中ZEN神经元胞体的分布图。在背角或腹角局部注射硒化钠后，ZnSeAMG标记的ZEN神经元出现在 Rexed板层V、VII和X，而板层I和II没有。在其余板层中观察到一些散在的ZEN胞体。标记的神经元在形状和大小上有所不同，注射部位周围标记胞体的相对高水平表明许多ZEN神经元具有相对较短的轴突或在靠近神经元起源处有过路终扣。超微结构上，在ZEN胞体和近端树突的溶酶体中发现了逆行运输的硒化锌簇。电子显微镜研究还揭示了两种不同类型的ZEN终末：（1）具有扁平突触小泡并形成对称突触接触的终末；（2）具有圆形小泡并形成不对称突触接触的终末。本研究表明存在ZEN神经元的脊髓固有系统，包括节段性和节段间的ZEN连接，并且具有抑制性或兴奋性的ZEN终末。ZEN神经元似乎形成了一个主要位于灰质中，但也与伸向白质的树突接触的庞大终末网络。从我们目前的知识中无法推断出这个相当庞大的ZEN终末系统的重要功能，但这些系统似乎参与了运动和感觉功能。
